Drilling tool

ABSTRACT

A drilling tool is disclosed. The drilling tool has a shaft and a pot-shaped base body. Chisel cutters are inserted into the annular front surface of the base body which is open on a drilling side. At least one suction opening is provided offset radially from an axis of the hammer core bit in the base of the base body facing away from the drilling side. The drilling dust can be suctioned out of the base body through the suction openings.

This application claims the priority of German Patent Document No. 10 2010 028 302.9, filed Apr. 28, 2010, the disclosure of which is expressly incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a drilling tool for percussive or rotary percussive processing of stone, concrete or other rock-like materials of the building and construction industry.

The bore-chiseling drilling tool according to the invention has a shaft and a pot-shaped base body. Chisel cutters are inserted into an annular front surface of the base body that is open on a drilling side. At least one suction opening is provided offset radially from an axis of the hammer core bit in the base of the base body facing away from the drilling side. The drilling dust can be suctioned out of the base body through the suction openings.

At least one suction opening can run in the drilling direction toward an axis of the base body, i.e., run diagonally toward the axis. The shaft may abut the base with a conically widening foot and the suction opening may run through the foot.

The chisel cutters may be made of hard metal. In one embodiment, the cutting surfaces of a group of chisel cutters are oriented radially and the cutting surfaces of another group of the chisel cutters are oriented tangentially to the front surface. The two groups of chisel cutters are oriented differently to the circumference each by 90 degrees. The forces occurring during chiseling and the rotational offsetting of the chisel cutters are introduced to some extent in a different manner to the base body and its base because of the two groups. Based on continuous load tests of core bits with chisel cutters arranged in this manner, it is assumed that more efficient removal and a lower mechanical load of the base can be achieved hereby.

A rod-shaped centering drill may be arranged on the axis within the pot-shaped base body.

One embodiment provides that the suction openings are arranged at a distance from the axis that is between 30% and 70% of the radius of the base body. A maximum of five suction openings may be provided; with a greater number, the base becomes soft and can dampen shocks.

One embodiment provides that a suction tube be arranged coaxially to the shaft and a suction opening abuts the base in an enclosing manner at least in sections. An outside diameter of the suction tube can be less than an outside diameter of the base body. The suction tube may have an elastic bellows or telescoping sleeve, whose annular end touches the base at least in sections. Lateral openings may be provided in the bellows or the telescoping sleeve through which air may be sucked in. The suction tube may have first sections and second sections circumferentially on its annular front surface pointing in the drilling direction, where the first sections project in the drilling direction by a maximum of 3 mm as compared to the second sections. The first sections or elevations space the suction tube apart from the base in such a way that slots are produced between the second sections and the annular front surface. A percentage of the first sections on the circumference of the front surface is, for example, between 10% and 20%.

One embodiment provides that ribs projecting toward the axis are arranged within the suction tube, whose facets pointing toward the axis touch the shaft.

The following description explains the invention on the basis of exemplary embodiments and figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section of a drilling tool;

FIG. 2 is a top view of the drilling tool;

FIG. 3 is a detailed view of an embodiment of a front end of a suction tube of the drilling tool; and

FIG. 4 is a detailed view of an alternative embodiment of a front end of a suction tube of the drilling tool.

DETAILED DESCRIPTION OF THE DRAWINGS

Unless otherwise indicated, the same or functionally equivalent elements are indicated by the same reference numbers in the figures.

FIG. 1 shows a longitudinal section of a hammer core bit 1 and FIG. 2 shows a top view. The hammer core bit 1 has several chisel cutters 2, which are inserted into an annular front surface 3 of a cylindrical base body 4. The chisel cutters 2 are preferably made of hard metal, e.g., of sintered composition material with tungsten carbide, and are suitable for a chiseling and cutting removal of stone, concrete or mineral construction materials. The chisel cutters 2 project beyond the front surface 3 in the drilling direction 5. The chisel cutters 2 may have one or two cutting surfaces 6 inclined to the front surface 3 of the base body 4. In a preferred embodiment, the chisel cutters 2 are inserted into the front surface 3 in different orientations. Whereas, in the case of a first group of the chisel cutters 2, the cutting surfaces 6 run in a radial direction, in the case of a second group, the cutting surfaces 6 are aligned tangentially to the annular front surface 3. The different alignment has proven to be advantageous in terms of the distribution of shock waves in percussive drilling. A radial dimension of the chisel cutters 2 may be greater than a thickness of the front surface 3, i.e., the difference between an outer and an inner radius. In particular, the chisel cutters 2 may project radially outwardly beyond the front surface 3 in order to define a drilling diameter.

A wall 9 radially limiting the cylindrical base body 4 is preferably completely closed. On a front surface facing away from the drilling side, a base 10 closes the base body 4 perpendicular to its axis 11.

A rod-shaped shaft 12 abuts the base 10 of the base body 4 in the extension of the axis 11. The shaft 12 and the base body 4 may be manufactured of one blank, i.e., without a joining seam or other connecting point. The shaft 12 may have a conically widening foot 13, which is connected to the base 10. An end section facing away from the base body 4 is configured to be an insertion end 15 with open and closed grooves for a rotary percussive power tool.

A blind hole 16 that runs coaxially to the axis 11 is introduced through the base 10 into the shaft 12. The blind hole 16 is used to accommodate a centering drill 17. The blind hole 16 may be conically tapering against the drilling direction 5 in such a way that the inserted centering drill 17 clamps in. A bore 18 crossing the blind hole 16 runs through the shaft 12. A user can push the centering drill out of the blind hole 16 by driving a pin into the bore. The centering drill 17 arranged on the axis 11 projects beyond the front surface 3 in the drilling direction 5.

Suction openings 19 are introduced in the base 10, which make it possible to suction from an interior space 20 of the base body 4. The suction openings 19 can weaken the mechanical stability of the hammer core bit 1, in particular with respect to the shocks initiated regularly in the base body 4 via the shaft 12 by the percussive hand-held power tool. The suction openings 19 are arranged at a distance 21 of between 30% and 70% of the outer radius of the base body 4 to the axis 11. In one embodiment, the suction openings 19 run inclined or diagonally toward the axis 11, wherein they run in the drilling direction 5 toward the axis 11. The suction openings 19 can preferably run through the foot 13 of the shaft 12. A diameter of the suction openings 19 can be, for example, in the range of 3 mm to 10 mm. A maximum of five suction openings 19 may be provided. The suction openings 19 may also be configured as elongated holes.

A suction tube 22 is put over the shaft 12 of the hammer core bit 1. A front end 23 of the suction tube 22 abuts the base 10 of the base body 4 on the outside and covers the suction openings 19. The front end is preferably formed by an elastic bellows 24. The elastic bellows 24 is used for compensation based on the tolerances of shafts 12 of different lengths. An outside diameter 25 of the bellows 24 is less than outside diameter 26 of the base body 4. An inside diameter of the bellows 24 is greater than the distance of the suction openings 19 to the axis 11 at least in the region of the contact surface with the base 10. Instead of a bellows 24, an axially displaceable sleeve may be arranged on the suction tube 22. The system of the suction tube 22 and sleeve is therefore telescoping and adaptable in terms of length to the length of the hammer core bit 1.

An annular front surface 28 of the front end 23 abuts the base 10 preferably only in sections and not as a closed ring (see detailed view in FIG. 3). The front surface 28 has several knobs 29 arranged in a distributed manner along its circumference, which project in the drilling direction 5. Several slots 30 form between the suction tube 22 and the base 10, through which air can be suctioned into the suction tube 22. The additional air flow can promote the air flow through the suction openings 19 or suction air along an outer side of the base body 4. The bearing surface of the front surface 28 on the base 10 amounts to only approx. 10% to 20% of the front surface 28 because of the projecting knobs 29. The slots 30 form between the non-supported areas of the front surface 28 and the base 10 of the hammer core bit 1. The slots 30 have a limited height (dimension along the axis 11), e.g., between 1 mm and 3 mm, and the knobs 29 are configured to be correspondingly high. In the case of a greater height of the knobs 29, the air flow through the suction openings 19 decreases noticeably and the cleaning capacity diminishes.

In another embodiment (FIG. 4), openings 30′ are provided near the front surface 28′. The openings 30′ have a cross-sectional area of 5 to 20 mm² for example. The openings 30′ may be provided in addition to or as an alternative to the slots 30. In the depicted embodiment, the front surface 28′ is flat and can abut the base 10 completely.

The preferably tubular suction tube 22 has an inside diameter which is greater than the shaft 12 of the hammer core bit 1 such that dust can be suctioned off between the suction tube 22 and the shaft 12. Ribs 31 projecting radially inwardly toward the axis 11 are provided to stabilize the suction tube 22. The six ribs 31 for example are arranged in different angular positions around the axis 11 and at the same height along the axis 11. The ribs 31 are preferably arranged equidistant around the axis 11, i.e., with six ribs 31, 60 degrees from one another respectively. The distance of the ribs 31 to the front surface 28 may be, for example, between 4 cm and 10 cm. A distance of the facets 32 pointing toward the axis 11 corresponds preferably to the radius of a standard shaft 12, e.g., 1 cm to 2 cm. The long suction tube 22, e.g., longer than 20 cm, can be supported laterally on the shaft 12.

The suction tube 22 is connected to a sleeve-shaped holder 33, which can be put over a tool receptacle of the power tool. The holder 33 is arranged in the axial extension to the suction tube 22. The section put over the tool receptacle can have a lateral window 37, though which the tool receptacle can be actuated.

The holder 33 may be fastened to a housing of the power tool with a clamping ring 34. The clamping ring 34 may be an integral part of a lateral hand grip 35. A rotation of the lateral hand grip 35 around its longitudinal axis actuates a pre-stressing mechanism of the clamping ring 34. In the depicted example, a snail pulls a section of the clamping ring 34 away from the axis 11 toward the lateral hand grip, thereby shortening the circumference of the clamping ring 34 and clamping the clamping ring 34 on the power tool. The holder 33 may have a contact area 36 with a cylindrical outer contour for applying the clamping ring 34. The contact area 36 may include an elastic plastic component.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 

1. A drilling tool, comprising: a shaft disposed on an axis of the drilling tool; a base body with an annular front surface and a base; and a suction opening in the base that is offset radially from the axis.
 2. The drilling tool according to claim 1, wherein the suction opening runs in a drilling direction toward the axis.
 3. The drilling tool according to claim 1, wherein the shaft abuts the base with a conically widening foot and wherein the suction opening runs through the foot.
 4. The drilling tool according to claim 1, further comprising a plurality of chisel cutters inserted into the annular front face and wherein the plurality of chisel cutters are made of hard metal.
 5. The drilling tool according to claim 4, wherein the plurality of chisel cutters have cutting surfaces, wherein the cutting surfaces of a group of the plurality of chisel cutters are oriented radially to the annular front surface, and wherein the cutting surfaces of another group of the plurality of chisel cutters are oriented tangentially to the annular front surface.
 6. The drilling tool according to claim 1, further comprising a centering drill arranged on the axis within the base body.
 7. The drilling tool according to claim 1, wherein the suction opening is arranged at a distance from the axis that is between 30% and 70% of a radius of the base body.
 8. The drilling tool according to claim 1, wherein a maximum of five suction openings are provided.
 9. The drilling tool according to claim 1, wherein a suction tube is arranged coaxially to the shaft and abuts the base.
 10. The drilling tool according to claim 9, wherein an outside diameter of the suction tube is less than an outside diameter of the base body.
 11. The drilling tool according to claim 9, wherein the suction tube has an elastic bellows and wherein an annular end of the elastic bellows abuts the base at least in sections.
 12. The drilling tool according to claim 9, wherein the suction tube has a plurality of first sections and a plurality of second sections circumferentially on an annular front surface, wherein the plurality of first sections projects a different distance from the annular front surface than the plurality of second sections.
 13. The drilling tool according to claim 12, wherein the plurality of first sections are arranged over 10% to 20% of the annular front surface.
 14. The drilling tool according to claim 9, wherein ribs projecting toward the axis are arranged within the suction tube.
 15. The drilling tool according to claim 9, wherein a front end of the suction tube defines an opening in the suction tube.
 16. The drilling tool according to claim 15, wherein a front surface of the suction tube is flat and wherein the front surface abuts the base. 